Means for effecting material and heat transfer



Feb. 5, 1946. A. G. DEEM 2,394,293

MEANS FOR EFFECTING MATERIAL AND HEAT TRANSFER Filed Nov. 8, 1940 2 Sheets-Sheetl Hyde Garvellfleem Feb. 5, 1946. A. G. DEEM MEANS FOR EFFECTING MATERIAL AND HEAT TRANSFER Filed Nov. 8 1940 2 Shets-Sheet 2 I [Que/21W Brae/2 GarreZZDee/n Patented Feb. 5, 1946 MEANS FOR EFFECTING MATERIAL AND HEAT TRANSFER Arden Garrell Deem, Urbana, Ill.

Application November 8, 1940, Serial No. 864,776

3 Claims.

My invention relates to means for the transfer I of matter and heat between a liquid and a gas phase.

One field of use of my invention is in operations involving gas and liquid contact.

The desideratum in gas and liquid contact operations is to bring, as speedily and intimately as possible, the individual particle of gas into contact with particles of liquid, or vice versa. Since both media are fluids, it is difficult to control the movements of the particles. The problem is to provide a Way of getting and keeping control of the particles of gas and of liquid so as to be able to compel their orderly movements to the end of getting the individual particles of gas contacted with particles of liquid, or vice versa.

Another field of use is conversion of a vapor into the liquid phase, or vice'versa. For evaporation, the Problem again is to provide a way of securing and maintaining control of the vapor particles and of the liquid particles to remove the vapor particles from the surface of the liquid to prevent return. Likewise for condensation, the

problem is to get and keep control of the parti cles of vapor and of liquid, so as to be able to bring the vapor particles rapidly and intimately in contact with liquid particles and keep them there.

Since in each case, motion of the particles of one fluid relative to the particles of the other is essential, some means for imparting motion is implicit in the solution of the problem. A liquid is distinguished from a gas or vapor in the limited degree of freedom of the particles or in other words, in the cohesion of the particles of a liquid as distinguished from the lack of cohesion in a gas or vapor.

According to one phase of my invention, I provide means for intensifying the characteristics of the respective fluids. To this end, I spread the liquid out in a thin film upon a solid wall. By its adhesive efiect, through wetting. it is bound to the wall, and has its mobility reduced. By its cohesive efiect it presents a thin substantially continuous body of small mass and large area.

The ga is more difficult to control. I move it by a vane and restrain its travel in a generally circular path whereby centrifuged force is developed.

Th'e driven body of gas is thereby pressedagainst the restraining circular wall, particularly on the forward surface of the vane. An area of reduced pressure is produced back of the vane.

The gas moves not only bodily with the vane, but.

also has an internal movement of eddying or ill churning. Now by forming the liquid film upon the circular restraining wall, I am able to hold the liquid in ideal condition for contact with the gas in the region of controlled movement of the gas. Thus I am able, as it were, to hold a thin film of liquid and scour it vigorously with a body of gas having a high degree of internal motion. Gravity flow of the film changes the surface particles of liquid. The scouring of the gas' along the liquid surfaces also imparts internal motion to the liquid.

According to the preferred form of apparatus embodying my invention, I provide a cylinder in which a blower blade or vane rotates with the outer edges of the blower blade in close proximity to the walls of the cylinder where the liquid is flowing in a thin film. The blower blade acting on the gasin the cylinder builds upa plenum of gas ahead of the blade and causes a reduction in pressure behind the blade, with the result that this differential in pressure forces the gas past the edge of the blade, and since the edge of the blade is near the film of liquid, a stream of gas is kept in motion adjacent the surface of the liquid. and a body of gas is caused to be scoured against the surface of the liquid ahead of the blade.

While the specific illustration and detailed description is directed to the art of distillation, it is to be understood that this is by way of exemplificatio-n and not by way of limitation. The invention is applicable to the absorption of one liquid phase, as for example, the absorption of CO2 by a slurry of sodium carbonate in water, or

, other suitable liquid media.

In the same fashion, the means may also be used for the deabsorption of gases or vapor from a solution, for

example, in the deabsorption of benzene vapor ,from straw oil by means of steam.

Likewise, the means may also be used to advantage in humidification or dehumidification operations, for example, in air conditioning where the h midification or dehumidification of air by importance.

water, which is maintained at a suitable temperature, is desired.

In the examples cited above, a net transfer of heat between the gas and liquid phase may or may not result. In general such transfer of heat may be considered as incidental to the operation of material transfer and depends upon the particular system under consideration. In the operation of partial condensation, as, {or exam le, vin the system water vapor-glycerine gvapor, it1-may be desired to condense the glycerine to aliquid with a minimum condensation of water. The means hereinafter described has been found tube of particular advantage in the operation .of partial condensation where the removal of heat is essential for the operation. Similarly. in the absorption of N02 in water to form nitric acid, followed by the deabsorption of the N reaction product, and subsequent reoxidation of the NO to N02 by air, in situ, the removal of heatis of great Here again the :means to :be :described is i of great advantage.

Also, while themeansherein disclosed are particularly applicable to theroperations of distillation, absorption, .deabsorption, :humidification, dehumidification and equilibrium partial condensation, the invention .is ;not limited torso-called diffusional .operations as will .be-apparenthereinafter.

New in order to acquaint thoseskilled in-the, art with the construction and operation :of a :specific embodiment of my invention, I shall describe, in ,conjunction with theaccompanying.drawingsthe means ,for embodying a specific example -of .my ,invention.

In .the drawings:

figure 1 .isa verticalsectional viewnf thefidevice .of my invention;

Figure 2 is asection on line 2- 2 of Figure 1;

Figure 3 is a fragmentary vertical sectional view of the device of Figure lhshowingla-mcdified term of discharge opening .for the gases;

Figures 4, Sand .6 are sectional views .of mod-i- -fled forms .cf impellers;

Fi ure -7is an .elevational view .of a portion .of

another modified .form of impeller;

Figure 8 is a bottom view of one section .of the imp ller shown in Figure 57; and

,FigureB is a verticailsectional view of another term of impeller.

The structural features and .mode of operation ,of a specific embodiment .of my invention or .per-

forming a distilling operation will .now be described.

Refer ing to Figure l, the device comprises .a

vertically .disposed casing I closed at the lower t nd bvau inScIt2,and.at the upper .endbya head .3 suitably secured to. th flange 'Lmounted at the upper end of the casing. An impeller is rotatably .m ntedin the casing bvmeans of .a shaft 6 at the upper end of the impeller and carried in I the radial and thrust bearingl. The hearing I countered, the cooling fins may be replaced by a Water jacket if desired.

A vapor inlet communicates with the lower end of the casing, and a vapor outlet (6 is provided in the head 3 at the upper end of the casing. A connection I1 is provided for the introduction of the reflux liquid into the apparatus. The liquid enters the channel 19 in the flange 4 and flows through the serrations or weir notches 20 which are cut the projecting tube periphery and down the inner wall ofthe casing in a thin uniform film adhering to the wall and draining through discharge opening 2| at the bottom of the casing.

The rate of feed of liquid to the channel i9 is suchthat all theliquid flows down as a film and the formation of any free liquid bodies as drops ;or.:1-ree particles is .avoided.

In the operation of the apparatus as an enrichingiractionating column, the mixed vapors to be fractionated .are introduced at l 5 and are caused inch .1. D. casing. The most desirable speed,

however, is from 1,700 to 4,0001R.P. M. In this connection it should be observed that the impeller width is specifically of such dimension as to allow .iree passage of the gas around the blade tip .and also .to permit the reflux to flow downward undisturbed on the casing wall. This relationship-is shown inFigures l and 2.

The impeller does not operate upon liquid but only upon the gaseous medium which may be a .gas .or vapor -or mixture -.of .gas and vapor. .No

free or unattached bodies or particles of liquid are allowed to form, and hence with all the rapid movement .Ofgas or vapor over thesurtace of the film of liquid, vno liquid as :such is=carried over.

In the operation of the device, rotation of the impeller .in the direction of the arrows builds up a plenum of. gas. ahead of the blade tips 'in the region A (Figure 2) and causes a rarefaction of gas in the region B, after the blade tips. This difference in pressure causes the gas to pass by the blade tips in the direction of the arrow 0. This action brings thecurrent of gas inclose contact with the liquid and keeps the molecules 'of gas which come in physical contact with the liquid in motion. At the same time a body of gas held by centrifugal force against the inner .pe-'

riphal wet surface of the casing cylinder I :is driven ahead of the vane. This body of gas tends to have a fairly large internal movement of eddying -.or rolling on the surface of the liquid film. It is obvious that such active scouring of the film by the swirling and sweeping gas can not he obtained by draWingeas through a fan and tl'ien blowing itagainst a wall carrying the liquid.

. Lt is-omy the use of a vane rapidly passing close to the surface of the film, driving andyscouring may in some cases be passed through the apof humidification' or dehumidification, be essential. The specific requirements of concur-renter counter-current flow are, of course, well known to one skilled in the art. Accordingly, the gas paratus in the same general direction as that of the liquid, if desired. I

- The length and the diameter of the impeller may, of course, be varied'from the proportions shown. I

The apparatus as shown comprises a closed circuit for each of the fluids, but it is contemplated that either may be an open circuit. In the event that a liquid is being treated and the resultant gas is waste, the gas on passing through the apparatus may be discharged to the atmosphere; on the other hand, when the liquid on passing throughthe apparatus is waste, it can of course be run into the sewer. i

As a typical example of the results that may be obtained when the apparatus is used as a fractionating column, the data for the distillation of a mixture of benzene-ethylene dichloride at total reflux are shown in Tables I and II.

Table I [Speed of impeller 3,400 R. P. M.]

Mel fraction of benzene condensate Oc./min. of liquid condensate Mol fraction benzene in residue No. of actual 3i plates In Table II are shown similar data for an impeller speed of 1700 R. P. M.

Table II [Speed of impeller 1,700 B. P. M.]

(lo/min. of Mel fraction Mol fraction No. of liquid conbenzene in of benzene actual densate residue condensate plates These data show that for a given mixture and rate of through put an optimum speed exists. It is expected, therefore, that one skilled in the art will adjust the speed to give the optimum results for a given through put. By through put is meant the rate at which the fluids pass through the device.

In the results given in Tables I and II the impeller was 24 inches long. At the optimum of 5.0 plates, this corresponds to a. height for each plate of 4.8". In contrast to this except onal efiiciency, an empty 3" tube has a fractionating eiiiciency of one plate in 120 inches and when packed with Raschig rings, an efilciency of one plate every 12 to 24 inches. It should further be noted in addition to the exceptional efficiency of my apparatus, at rates of through put heretofore unattainable, that the pressure drop through the apparatus is essentially negligible. This absence of pressure drop is of particular importance in vacuum distillation.

In the above, the column was described as an enriching section. To one skilled in the art, the apparatus may also obviously be used as an exhausting section. Likewise, when both an enriching and an exhausting section are desired, two columns may be placed in tandem by suitable connections. By the same token when more theoretical plates are required than can be secured by one unit of the apparatus, as many units as desired may be placed in series by suitable interconnecting pipes. Alternatively, units may obviously be placed in parallel to secure any desired through put or capacity over and beyond that obtainable with one unit.

As before mentioned, the apparatus may be used for absorption with results manifold better than can be obtained by previous equipment. When used as an absorption column, the gases to'be treated enter at I5, pass through the apparatus, and leave at I6. The absorbing liquid enters at IT, flows down the casing wall as a thin film and leaves at 2|. Similarly, in air conditioning, the air to be dehumidified and cooled enters at l5 and leaves at I6, while the cooling water enters at I! and leaves at 2|.

In the general cases of distillation, absorption,

deabsorption, humidification, and dehumid fication, it is usually desired that the apparatus be rendered adiabatic by a suitable covering of insulating material such as'magnesia. The insulating material may be replaced by a heat transfer medium, either for supplying heat or removing heat from the walls of the chamber, to suit particular operations. In the production of nitric acid by the absorption of N02 in water, it is particularly desirable that the reaction be carried out with external cooling. Such cooling means conveniently may be supplied by replacing the magnesia insulation with a cooling jacket of any suitable form. Likewise, in the case of humid fication it might be desirable to supply heat to the walls of the chamber, in which case a heating jacket of suitable form may be fitted on the device.

In Figure 5, a'jacket 22 is shown fragmentarily, which may be a heat transfer medium, either for supplying heat to or removing heat from the easing wall, or an insulating medium.

When used a a partial condenser, the above mentioned cooling jacket is of course provided.

The mixed vapor enters at l5 and the denuded vapor leaves at Hi. In this case connection I! is unnecessary as the condensate only is withdrawn at 2|.

In Figure 3 I have shown fragmentarily a device similar to that of Figure 1, but with the vapor outlet l6 connected tangentially to the head 3. This type of discharge opening more readily accommodates the swirling motion of the gas.

As is apparent from the foregoing, the designer is allowed considerable latitude in the adaptations of the apparatus without departing from the spirit of my invention. As a further example of the modifications, possible alternative impeller forms are shown in Figures 4 to 6, inclusive. These impeller forms, instead of being solid blade impellers as shown in Figure each comprises a shaft 24 to which are secured blades 25. Figure 4 illustrates a straight radial blade while Figure 5 is a concave backward blade, and Figure 6 a concave forward blade.

Another form of impeller is shown in Figure '7, wh ch comprises a series of blower elements 26 mounted on a shaft. The number of blower elements may be varied to suit the particular conditions under which the device is to be used.

oriorward or backward concave, as may he desired. The lower plate 28 is .of such diameter as -to;azllow only :suiiicient'clearance at the wall of the casing to permit the reflux liquidto flow downward undisturbed. The upper plate 21 should he .sulliciently smaller than the lower plate elements. Openings 3! are provided in the lower plate 28 for the ventrance'oi gas to the blower element.

Figure 9 shows :a form :of centrifugal compressor unit. The number of these units, as inthe caseof the type shown in Figures 7 and 8, will depend onwthe :particular conditions encountered in use of the apparatus. The :unit comprises a throat disc :33 with openings 34 therein located near the :center thereof for the passage of gas through theimpellergan upper disc 35, andblades 36 positioned last-ween the discs. The throat disc 33, as in the previous forms, isz'of such diameter that a smallspace is-left between itand the Wall of the casing only sufficient to allow the liquidto fall undisturbed, while the-upper disc .35 i somewhat smallerin-diameterrte-allow the ,free escape of gas; The opening 31 being smaller in vertical dimension than the-space in the interior of the unit provides greater velocity of the gas on leaving the unit and-striking the surface of the liquid.

One great advantage of my aupaaatus in addi tiontotheunusua-lly high capacity, low hold up, low pressure drop, and high efiiciency is that great economy is eflt'ected in. the building height required to house the-equipment. in general, this is a factor of considerable magnitude.

It is tobeunderstood that the specificembodiment :and the modified forms of the apparatus herein shown anddescribed are to be considered as exemplary only, and not limiting, and that variouschanges in details and rearrangement of parts therein .may be made without departing r;

from the spirit-and scope of the invention.

I claim: I 1. Means for contacting gas and liquidwhich iEachblower element :consists .of ansupper plate -2.?! and a lower plateiz2 8 "between which are/ secured blades 30; These blades may :be straight,

--cnmprises .a vertical cylinder into-which gaseous -fiuid-isadapted to new, means for depositing'liquid in the form of a filmupon the inner surface of the cylinder and allowing the same to gravitate downwardlyzsaid means comprising a .cir-

cumferential distributing channel at the upper end of the cylinder and a liquid supply'meansextending thereto for supplying liquid at a rate which will maintain said film without formation of free liquid. and a rotatably mounted gas impeller in the cylinder for moving gaseous fluid at .high velocity along-the surface of said film, said impeller being free of contact with the liquid, said cylinder being substantially free of unattached bodies of liquid.

.2. Means iorcontacting gas and liquid which comprises a vertical cylinder into which gaseous fiuidzis adapted to flow, means for depositing liquid in the form of a film upon the inner surface ,Qf the cylinder .and allowing the same togravitate downwardly, said means comprising an open channel with spaced entry ports to the inner surface of the cylinder, and a rotatably mounted gas impeller-in the cylinder for moving gaseous fluid at high velocity along the surface of said film, said impeller being free of contact with the liquid.

3., In combination,a chamber for gaseous fluid having a wall provided with an inner surface which extends in a generally vertical direction, liquid distributing means having a liquid inlet, and having liquid outlets for discharging liquids upon the surface ofthe wall of the chamber, said outlets distributing said liquid upon the upper part of the wall surface in the form of a liquid film adhering to the surface of the wall and held thereto by the adhesion of the liquid of the film to said surface, but capable of flowing downwardly'along-said surface under the influence of gravity, a gaseous fiuid'agitator having a vane now able along the wall transversely of the downward flow of the film .of liquid,.said agitator vane being mounted to sweep along the wall, but out of contact with the liquid film, means for supplying gaseous fluid to that portion of the chamber in which said agitator moves, and an outlet for discharging gaseous fluid from the chamber.

ARDEN GARRELL DEEM. 

